Re: Droping indexes - Mailing list pgsql-sql

From Mario Behring
Subject Re: Droping indexes
Date
Msg-id 754782.38721.qm@web30006.mail.mud.yahoo.com
Whole thread Raw
In response to Droping indexes  (Mario Behring <mariobehring@yahoo.com>)
Responses Re: Droping indexes  (Alvaro Herrera <alvherre@commandprompt.com>)
List pgsql-sql
Hi Tomas,

Thank you.

Please help me here.....I am not a database guy...........how do I use this CLUSTER command and what does it do? Please keep in mind that I do not have disk space left.........

Also, please check the table I am talking about below:

opennms=# \d events
                        Tabela "public.events"
         Colunm          |            Type             | Modifyers
-------------------------+-----------------------------+---------------
 eventid                 | integer                     | not null
 eventuei                | character varying(256)      | not null
 nodeid                  | integer                     |
 eventtime               | timestamp without time zone | not null
 eventhost               | character varying(256)      |
 eventsource             | character varying(128)      | not null
 ipaddr                  | character varying(16)       |
 eventdpname             | character varying(12)       | not null
 eventsnmphost           | character varying(256)      |
 serviceid               | integer                     |
 eventsnmp               | character varying(256)      |
 eventparms              | text                        |
 eventcreatetime         | timestamp without time zone | not null
 eventdescr              | character varying(4000)     |
 eventloggroup           | character varying(32)       |
 eventlogmsg             | character varying(256)      |
 eventseverity           | integer                     | not null
 eventpathoutage         | character varying(1024)     |
 eventcorrelation        | character varying(1024)     |
 eventsuppressedcount    | integer                     |
 eventoperinstruct       | character varying(1024)     |
 eventautoaction         | character varying(256)      |
 eventoperaction         | character varying(256)      |
 eventoperactionmenutext | character varying(64)       |
 eventnotification       | character varying(128)      |
 eventtticket            | character varying(128)      |
 eventtticketstate       | integer                     |
 eventforward            | character varying(256)      |
 eventmouseovertext      | character varying(64)       |
 eventlog                | character(1)                | not null
 eventdisplay            | character(1)                | not null
 eventackuser            | character varying(256)      |
 ndices:ktime            | timestamp without time zone |
    "pk_eventid"primary key, btree (eventid)
    "events_acktime_idx" btree (eventacktime)
    "events_ackuser_idx" btree (eventackuser)
    "events_display_idx" btree (eventdisplay)
    "events_ipaddr_idx" btree (ipaddr)
    "events_log_idx" btree (eventlog)
    "events_nodeid_idx" btree (nodeid)
    "events_serviceid_idx" btree (serviceid)
    "events_severity_idx" btree (eventseverity)
    "events_time_idx" btree (eventtime)
    "events_uei_idx" btree (eventuei)
Restrictions of foreing key:
    "fk_nodeid6" FOREIGN KEY (nodeid) REFERENCES node(nodeid) ON DELETE CASCADE


Thanks.

Mario Behring





----- Original Message ----
From: Tomas Vondra <tv@fuzzy.cz>
To: Mario Behring <mariobehring@yahoo.com>
Sent: Tuesday, January 16, 2007 12:29:59 PM
Subject: Re: [SQL] Droping indexes

> Hi all,
>
> Please, if I drop all indexes from a table, can I recreate them after
> performing a vacuum full at this table? I mean, I do not know details
> about the indexes, so what I am asking is if I issue a REINDEX on this
> table, will it  create the proper indexes again?
>
> Please advise.

No, if you drop them they're lost and you'll have to recreate them using
CREATE INDEX. Being in your situation, I'd use CLUSTER instead of VACUUM
+ REINDEX, as it basically does the same thing, plus it has several
advantages related to performance.

Just think carefully which index would you use to cluster the table -
the index associated with the primary key is generally a good choice.

Tomas

PS: Don't forget to analyze the table after that!



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